JP2006214370A - Exhaust emission control device - Google Patents

Exhaust emission control device Download PDF

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JP2006214370A
JP2006214370A JP2005028660A JP2005028660A JP2006214370A JP 2006214370 A JP2006214370 A JP 2006214370A JP 2005028660 A JP2005028660 A JP 2005028660A JP 2005028660 A JP2005028660 A JP 2005028660A JP 2006214370 A JP2006214370 A JP 2006214370A
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exhaust
fuel
reduction catalyst
throttle means
storage reduction
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Hiroshi Funahashi
博 舟橋
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Hino Motors Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently regenerate NOx storage reduction catalyst by adding the necessary minimum fuel. <P>SOLUTION: In this exhaust emission control device, the NOx storage reduction catalyst 10 is provided in the midway of an exhaust pipe 9, and fuel is added as a reducing agent to the upstream side of the NOx storage reduction catalyst 10. The device includes: a butterfly valve 11 as an exhaust emission throttle means for suitably throttling the exhaust flow rate on the upstream side from the NOx storage reduction catalyst 10 in the exhaust pipe 9; an injector 14 provided as a fuel adding means for adding fuel into the exhaust pipe 9 immediately after the butterfly valve 11; and a control device 16 for throttling the above in decelerating a vehicle to perform addition of fuel to the injector 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、排気浄化装置に関するものである。   The present invention relates to an exhaust emission control device.

従来より、排気管の途中に装備した排気浄化用触媒により排気浄化を図ることが行われており、この種の排気浄化用触媒としては、排気空燃比がリーンの時に排気ガス中のＮＯxを酸化して硝酸塩の状態で一時的に吸蔵し、排気ガス中のＯ2濃度が低下した時に未燃ＨＣやＣＯ等の介在によりＮＯxを分解放出して還元浄化する性質を備えたＮＯx吸蔵還元触媒が知られている。 Conventionally, exhaust purification is carried out with an exhaust purification catalyst installed in the middle of the exhaust pipe. As this type of exhaust purification catalyst, NOx in exhaust gas is oxidized when the exhaust air-fuel ratio is lean. Thus, a NOx occlusion reduction catalyst having the property of temporarily storing in the form of nitrate and decomposing and releasing NOx through the intervention of unburned HC, CO, etc. when the O 2 concentration in the exhaust gas decreases is reduced and purified. Are known.

この種のＮＯx吸蔵還元触媒としては、白金・バリウム・アルミナ触媒や、白金・カリウム・アルミナ触媒等が前述した如き性質を有するものとして既に知られている。   As this type of NOx occlusion reduction catalyst, platinum / barium / alumina catalyst, platinum / potassium / alumina catalyst, and the like have already been known.

そして、ＮＯx吸蔵還元触媒においては、ＮＯxの吸蔵量が増大して飽和量に達してしまうと、それ以上のＮＯxを吸蔵できなくなるため、定期的にＮＯx吸蔵還元触媒に流入する排気ガスのＯ2濃度を低下させてＮＯxを分解放出させる必要がある。 In the NOx occlusion reduction catalyst, when the occlusion amount of NOx increases and reaches the saturation amount, no more NOx can be occluded, and therefore, O 2 of the exhaust gas flowing into the NOx occlusion reduction catalyst periodically. It is necessary to decompose and release NOx by reducing the concentration.

例えば、ガソリン機関に使用した場合であれば、機関の運転空燃比を低下（機関をリッチ空燃比で運転）することにより、排気ガス中のＯ2濃度を低下し且つ排気ガス中の未燃ＨＣやＣＯ等の還元成分を増加してＮＯxの分解放出を促すことができるが、ＮＯx吸蔵還元触媒をディーゼル機関の排気浄化装置として使用した場合には機関をリッチ空燃比で運転することが困難である。 For example, when used in a gasoline engine, the operating air-fuel ratio of the engine is reduced (the engine is operated at a rich air-fuel ratio), thereby reducing the O 2 concentration in the exhaust gas and unburned HC in the exhaust gas. It is possible to promote the decomposition and release of NOx by increasing reducing components such as CO and CO. However, when the NOx storage reduction catalyst is used as an exhaust purification device of a diesel engine, it is difficult to operate the engine at a rich air-fuel ratio. is there.

このため、エンジン側でも燃料噴射制御による低λ運転（λ：空気過剰率）を極力行いつつＮＯx吸蔵還元触媒の上流側で排気ガス中に燃料（ＨＣ）を添加し、この添加燃料を還元剤としてＮＯx吸蔵還元触媒上でＯ2と反応させることで排気ガス中のＯ2濃度を低下させる必要があった（例えば、特許文献１参照）。
特開２０００−３５６１２７号公報 Therefore, fuel (HC) is added to the exhaust gas on the upstream side of the NOx storage reduction catalyst while performing low λ operation (λ: excess air ratio) by fuel injection control as much as possible on the engine side, and this added fuel is used as a reducing agent. As a result, it was necessary to reduce the O 2 concentration in the exhaust gas by reacting with O 2 on the NOx storage reduction catalyst (see, for example, Patent Document 1).
JP 2000-356127 A

しかしながら、このように燃料添加により排気ガス中の酸素濃度を低下させてＮＯx吸蔵還元触媒の再生を図る方式では、エンジン側での低λ運転に加えて燃料添加を実施することにより燃料消費量が多く必要となって大幅な燃費悪化を招くという問題があり、特に排気ガスの流量が多く且つ流速が高い条件下では、ＮＯx吸蔵還元触媒周囲の雰囲気中におけるＯ2濃度を下げるのに多量の燃料添加が必要となる上、そのような多量の燃料添加を実施してもなお十分なＮＯx吸蔵還元触媒の再生を図ることが困難となっていた。 However, in this method of reducing the oxygen concentration in the exhaust gas by adding fuel and regenerating the NOx storage reduction catalyst, fuel consumption is reduced by performing fuel addition in addition to low λ operation on the engine side. There is a problem that a large amount of fuel is required, leading to a significant deterioration in fuel consumption. Particularly under conditions where the exhaust gas flow rate is high and the flow velocity is high, a large amount of fuel is required to reduce the O 2 concentration in the atmosphere around the NOx storage reduction catalyst. In addition, it is difficult to regenerate the NOx occlusion reduction catalyst even when such a large amount of fuel is added.

本発明は、上述の実情に鑑みてなされたものであり、必要最小限の燃料の添加により効率良くＮＯx吸蔵還元触媒を再生し得るようにすることを目的としている。   The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to efficiently regenerate a NOx storage reduction catalyst by adding a minimum amount of fuel.

本発明は、排気流路の途中にＮＯx吸蔵還元触媒を装備し且つ該ＮＯx吸蔵還元触媒の上流側に還元剤として燃料を添加してＮＯxを還元浄化するように構成した排気浄化装置であって、前記排気流路におけるＮＯx吸蔵還元触媒より上流側に排気流量を適宜に絞り込む排気絞り手段を備えると共に、該排気絞り手段の直後に排気流路内に燃料を添加する燃料添加手段を設け、前記排気絞り手段を車両の減速時に絞り込んで前記燃料添加手段に燃料添加を実行せしめる制御装置を備えたことを特徴とするものである。   The present invention is an exhaust emission control device equipped with a NOx storage reduction catalyst in the middle of an exhaust passage and configured to reduce and purify NOx by adding fuel as a reducing agent upstream of the NOx storage reduction catalyst. An exhaust throttle means for appropriately reducing the exhaust flow rate upstream of the NOx storage reduction catalyst in the exhaust flow path, and a fuel addition means for adding fuel into the exhaust flow path immediately after the exhaust throttle means, The exhaust gas throttle means is throttled at the time of deceleration of the vehicle, and a control device is provided for causing the fuel addition means to perform fuel addition.

而して、このようにすれば、車両が減速する度に排気絞り手段が絞り込まれてＮＯx吸蔵還元触媒の周囲を流れる排気（気筒から排気通路側へ排出された圧縮空気：減速時はアクセルオフにより燃料噴射なし）の流量が微少となり、この微少な流量の排気に対し従来より少ない燃料添加を行うだけでＮＯx吸蔵還元触媒周囲の雰囲気中におけるＯ2濃度が効果的に低下し、しかも、ＮＯx吸蔵還元触媒周囲の排気の流速も極度に遅くなって十分な反応時間が確保されるので、必要最小限の燃料添加により効率良くＮＯx吸蔵還元触媒の再生を図ることが可能となる。 Thus, when the vehicle is decelerated, the exhaust throttling means is throttled and exhaust flowing around the NOx storage reduction catalyst (compressed air discharged from the cylinder to the exhaust passage side: accelerator off during deceleration) The amount of O 2 in the atmosphere around the NOx storage reduction catalyst is effectively reduced by adding only a small amount of fuel to the exhaust gas at a low flow rate. Since the flow rate of the exhaust gas around the storage reduction catalyst is extremely slow and a sufficient reaction time is secured, it is possible to efficiently regenerate the NOx storage reduction catalyst with the minimum amount of fuel added.

また、本発明においては、排気絞り手段をバタフライ弁により構成し、該バタフライ弁の閉時に確保される最小開度の隙間の直後に燃料添加手段の添加口を配置すると良く、このようにすれば、バタフライ弁により流れを堰き止められて昇圧した排気と略同じ高温高圧の排気が前記隙間から流出することになる。   Further, in the present invention, the exhaust throttle means may be constituted by a butterfly valve, and the addition port of the fuel addition means may be disposed immediately after the gap of the minimum opening secured when the butterfly valve is closed. Exhaust gas at approximately the same high temperature and high pressure as the exhaust gas whose pressure has been blocked by the butterfly valve is discharged from the gap.

そして、この隙間の直後に添加される燃料は、高温による霧化の促進作用と、高流速の流れ及びその周りからの渦の取り込みによる霧化の促進作用とを相乗的に受け、添加燃料から成るＨＣミストの軽量小粒化が促進され、ＮＯx吸蔵還元触媒に達して直ぐにガス化して酸化反応を起こし易い状態となる。   The fuel added immediately after the gap is synergistically subjected to the atomization promoting action due to the high temperature and the atomization promoting action due to the flow of the high flow velocity and the vortex from the surroundings. As a result, the HC mist is made lighter and smaller and reaches the NOx occlusion / reduction catalyst and immediately gasifies to easily undergo an oxidation reaction.

尚、本発明における排気絞り手段は、例えば、排気ブレーキを兼用したものであっても良く、このようにすれば、既存の排気ブレーキを有効に活用することで新たな排気絞り手段を別途設けなくて済む。   The exhaust throttle means in the present invention may be, for example, also used as an exhaust brake. In this way, a new exhaust throttle means is not separately provided by effectively utilizing the existing exhaust brake. I'll do it.

また、本発明においては、吸気流路に吸気流量を適宜に絞り込む吸気絞り手段を備え、該吸気絞り手段を車両の減速時に排気絞り手段と一緒に絞り込むように構成することも可能である。   In the present invention, it is also possible to provide an intake throttle means for appropriately reducing the intake flow rate in the intake flow path, and to restrict the intake throttle means together with the exhaust throttle means when the vehicle is decelerated.

このようにした場合には、減速時に吸気絞り手段により吸気流量が同時に絞り込まれるので、排気絞り手段で排気の流れが堰き止められることによる排気抵抗の増加作用（排気ブレーキの作用）が得られなくなり、エンジン側でのポンピングロスが喪失して単なるフリクションのみの惰性運転となる結果、車両の減速時に運転者が意図しない制動力がかかることがなくなる。   In this case, since the intake air flow rate is simultaneously throttled by the intake throttle means at the time of deceleration, an exhaust resistance increasing action (exhaust brake action) can no longer be obtained by blocking the exhaust flow by the exhaust throttle means. As a result of the loss of pumping loss on the engine side and the inertial driving with only the friction, the braking force unintended by the driver is not applied when the vehicle decelerates.

上記した本発明の排気浄化装置によれば、下記の如き種々の優れた効果を奏し得る。   According to the exhaust emission control device of the present invention described above, various excellent effects as described below can be obtained.

（Ｉ）本発明の請求項１に記載の発明によれば、従来より少ない燃料添加を行うだけでＮＯx吸蔵還元触媒周囲の雰囲気中におけるＯ2濃度を効果的に低下し且つ十分な反応時間を確保することができるので、必要最小限の燃料添加により効率良くＮＯx吸蔵還元触媒を再生することができ、ＮＯx吸蔵還元触媒を用いた排気浄化装置における燃費の悪化を従来より大幅に軽減することができる。 (I) According to the invention described in claim 1 of the present invention, the O 2 concentration in the atmosphere around the NOx occlusion reduction catalyst can be effectively reduced and sufficient reaction time can be obtained by adding less fuel than in the prior art. As a result, the NOx storage reduction catalyst can be efficiently regenerated by adding the minimum amount of fuel, and the deterioration of fuel consumption in the exhaust purification system using the NOx storage reduction catalyst can be greatly reduced as compared with the prior art. it can.

（ＩＩ）本発明の請求項２に記載の発明によれば、添加燃料から成るＨＣミストの軽量小粒化を促進し、該ＨＣミストがＮＯx吸蔵還元触媒で直ぐにガス化して酸化反応を起こし易くなるようにすることができるので、添加燃料のＮＯx吸蔵還元触媒上での反応性を更に向上することができて、より一層効率の良いＮＯx吸蔵還元触媒の再生を実現することができる。   (II) According to the invention described in claim 2 of the present invention, the HC mist composed of the added fuel is promoted to be light and small, and the HC mist is readily gasified by the NOx occlusion reduction catalyst to easily cause an oxidation reaction. Therefore, the reactivity of the added fuel on the NOx storage reduction catalyst can be further improved, and the NOx storage reduction catalyst can be more efficiently regenerated.

（ＩＩＩ）本発明の請求項３に記載の発明によれば、排気ブレーキを要する車両である場合に、既存の排気ブレーキを有効に活用することで新たな排気絞り手段を別途設けなくて済むので、車両の減速時に排気流量を絞り込んでＮＯx吸蔵還元触媒への燃料添加を行う排気浄化装置の実施コストを著しく削減することができる。   (III) According to the invention described in claim 3 of the present invention, when the vehicle requires an exhaust brake, it is not necessary to separately provide a new exhaust throttle means by effectively utilizing the existing exhaust brake. Further, it is possible to remarkably reduce the implementation cost of the exhaust gas purification device that throttles the exhaust gas flow rate when the vehicle decelerates and adds fuel to the NOx storage reduction catalyst.

（ＩＶ）本発明の請求項４に記載の発明によれば、排気絞り手段で排気の流れが堰き止められることによる排気抵抗の増加作用（排気ブレーキの作用）をなくし、エンジン側でのポンピングロスを零として単なるフリクションのみの惰性運転とすることができるので、車両の減速時に運転者の意図しない制動力がかかることを回避してドライバビリティを良好に維持することができる。   (IV) According to the invention described in claim 4 of the present invention, the exhaust resistance increasing action (exhaust brake action) caused by the exhaust flow being blocked by the exhaust throttle means is eliminated, and the pumping loss on the engine side is eliminated. Since it is possible to perform inertial driving with only friction with zero, it is possible to avoid the application of braking force not intended by the driver when the vehicle is decelerated and to maintain good drivability.

以下本発明の実施の形態を図面を参照しつつ説明する。   Embodiments of the present invention will be described below with reference to the drawings.

図１及び図２は本発明を実施する形態の一例を示すもので、図１中における符号の１はターボチャージャ２を搭載したディーゼルエンジンを示しており、エアクリーナ３から導いた吸気４を吸気管５を通し前記ターボチャージャ２のコンプレッサ２ａへ導いて加圧し、その加圧された吸気４をインタークーラ６を介しディーゼルエンジン１の各気筒に分配して導入するようにしてある。   1 and 2 show an example of an embodiment for carrying out the present invention. Reference numeral 1 in FIG. 1 denotes a diesel engine equipped with a turbocharger 2, and intake air 4 guided from an air cleaner 3 is taken into an intake pipe. 5 is introduced to the compressor 2a of the turbocharger 2 and pressurized, and the pressurized intake air 4 is distributed and introduced to each cylinder of the diesel engine 1 via the intercooler 6.

そして、このディーゼルエンジン１の各気筒から排気マニホールド７を介し排出された排気ガス８を排気管９を通して前記ターボチャージャ２のタービン２ｂへ送り、該タービン２ｂを駆動した排気ガス８をＮＯx吸蔵還元触媒１０を通してＮＯxを低減した上で車外へ排出するようにしてある。   The exhaust gas 8 discharged from each cylinder of the diesel engine 1 through the exhaust manifold 7 is sent to the turbine 2b of the turbocharger 2 through the exhaust pipe 9, and the exhaust gas 8 driving the turbine 2b is sent to the NOx storage reduction catalyst. 10 is used to reduce NOx and discharge the vehicle outside the vehicle.

更に、前記ＮＯx吸蔵還元触媒１０の入側の排気管９に、排気流量を適宜に絞り込む排気絞り手段としてバタフライ弁１１から成る排気ブレーキ１２を備え、該排気ブレーキ１２におけるバタフライ弁１１の直後には、排気管９内に燃料を噴射する燃料添加手段としてインジェクタ１４を設け、このインジェクタ１４の添加口１５が、前記バタフライ弁１１の閉時に確保される最小開度の隙間１３（図２参照）の直後に配置されるようにしてある。   Further, the exhaust pipe 9 on the inlet side of the NOx occlusion reduction catalyst 10 is provided with an exhaust brake 12 comprising a butterfly valve 11 as an exhaust throttle means for appropriately reducing the exhaust flow rate, and immediately after the butterfly valve 11 in the exhaust brake 12. In addition, an injector 14 is provided as a fuel addition means for injecting fuel into the exhaust pipe 9, and an addition port 15 of the injector 14 is a gap 13 (see FIG. 2) having a minimum opening secured when the butterfly valve 11 is closed. It is arranged immediately after.

そして、これらバタフライ弁１１及びインジェクタ１４の作動は、エンジン制御コンピュータ（ＥＣＵ：Electronic Control Unit）を成す制御装置１６からの開度信号１１ａ及び噴射指令信号１４ａにより制御されるようになっており、ディーゼルエンジン１の機関回転数を検出する回転センサ１７からの回転数信号１７ａと、アクセルセンサ１８（アクセルペダルの踏み込み角度を検出するセンサ）からの負荷信号１８ａとから判断される現在の運転状態に基づいて、所定の回転数以上（車両が走行状態にある）でアクセルオフが確認された車両の減速時に、前記排気ブレーキ１２のバタフライ弁１１を閉じて前記インジェクタ１４に燃料添加を実行せしめるようになっている。   The operations of the butterfly valve 11 and the injector 14 are controlled by an opening signal 11a and an injection command signal 14a from a control device 16 constituting an engine control computer (ECU: Electronic Control Unit). Based on the current operating state determined from the rotation speed signal 17a from the rotation sensor 17 that detects the engine rotation speed of the engine 1 and the load signal 18a from the accelerator sensor 18 (sensor that detects the depression angle of the accelerator pedal). Thus, when the vehicle is decelerated at a predetermined speed or higher (the vehicle is in a running state) and the accelerator is turned off, the butterfly valve 11 of the exhaust brake 12 is closed to cause the injector 14 to perform fuel addition. ing.

ただし、ここで説明している車両の減速時における燃料添加は、ＮＯx吸蔵還元触媒１０の入側の排気温度を温度センサ１９で検出し、該温度センサ１９からの検出信号１９ａに基づいて、ＮＯx吸蔵還元触媒１０へ流入する排気の温度が所定の反応可能温度に達していることを確認した上で実行するようにしておく。   However, the fuel addition at the time of deceleration of the vehicle described here is performed by detecting the exhaust temperature on the inlet side of the NOx storage reduction catalyst 10 with the temperature sensor 19, and based on the detection signal 19a from the temperature sensor 19, the NOx. The process is performed after confirming that the temperature of the exhaust gas flowing into the storage reduction catalyst 10 has reached a predetermined reaction possible temperature.

而して、このように排気浄化装置を構成すれば、車両が減速する度に排気ブレーキ１２のバタフライ弁１１が絞り込まれてＮＯx吸蔵還元触媒１０の周囲を流れる排気（気筒から排気管９側へ排出された圧縮空気：減速時はアクセルオフにより燃料噴射なし）の流量が微少となり、この微少な流量の排気に対し従来より少ない燃料添加を行うだけでＮＯx吸蔵還元触媒１０周囲の雰囲気中におけるＯ2濃度が効果的に低下し、しかも、ＮＯx吸蔵還元触媒１０周囲の排気の流速も極度に遅くなって十分な反応時間が確保されるので、必要最小限の燃料添加により効率良くＮＯx吸蔵還元触媒１０の再生が図られることになる。 Thus, if the exhaust gas purification device is configured in this way, the exhaust valve 12 of the exhaust brake 12 is throttled every time the vehicle decelerates, and the exhaust gas flowing around the NOx storage reduction catalyst 10 (from the cylinder to the exhaust pipe 9 side). The flow rate of exhausted compressed air: no fuel injection due to accelerator off when decelerating) becomes very small. By adding less fuel to the exhaust gas at this small flow rate than in the past, Ox in the atmosphere around the NOx storage reduction catalyst 10 2 The concentration is effectively reduced, and the exhaust gas flow rate around the NOx storage and reduction catalyst 10 is extremely slow, so that a sufficient reaction time is secured. Therefore, the NOx storage and reduction catalyst can be efficiently performed with the minimum amount of fuel added. Ten reproductions are to be achieved.

この際、特に本形態例においては、バタフライ弁１１の閉時に確保される最小開度の隙間１３の直後にインジェクタ１４の添加口１５を配置しているので、バタフライ弁１１により流れを堰き止められて昇圧した排気と略同じ高温高圧の排気が前記隙間１３から流出することになり、この隙間１３の直後に添加される燃料が、高温による霧化の促進作用と、高流速の流れ及びその周りからの渦の取り込みによる霧化の促進作用とを相乗的に受けるので、添加燃料から成るＨＣミストの軽量小粒化が促進されることになり、該ＨＣミストがＮＯx吸蔵還元触媒１０に達して直ぐにガス化して酸化反応を起こし易い状態となる。   At this time, in particular, in the present embodiment, since the addition port 15 of the injector 14 is arranged immediately after the gap 13 having the minimum opening secured when the butterfly valve 11 is closed, the flow is blocked by the butterfly valve 11. The high-temperature and high-pressure exhaust that is substantially the same as the exhaust whose pressure has been increased in this way flows out of the gap 13, and the fuel added immediately after the gap 13 promotes the atomization promoting action due to the high temperature, the flow of high flow velocity and the surroundings. As a result, the HC mist consisting of the added fuel is promoted to become lighter and smaller. As soon as the HC mist reaches the NOx occlusion reduction catalyst 10, the atomization is accelerated. Gasification is likely to cause an oxidation reaction.

従って、上記形態例によれば、従来より少ない燃料添加を行うだけでＮＯx吸蔵還元触媒１０周囲の雰囲気中におけるＯ2濃度を効果的に低下し且つ十分な反応時間を確保することができるので、必要最小限の燃料添加により効率良くＮＯx吸蔵還元触媒１０を再生することができ、ＮＯx吸蔵還元触媒１０を用いた排気浄化装置における燃費の悪化を従来より大幅に軽減することができる。 Therefore, according to the above embodiment, the amount of O 2 in the atmosphere around the NOx storage reduction catalyst 10 can be effectively reduced and sufficient reaction time can be ensured by simply adding less fuel than in the past. The NOx occlusion reduction catalyst 10 can be efficiently regenerated by adding the minimum necessary amount of fuel, and the deterioration of fuel consumption in the exhaust gas purification apparatus using the NOx occlusion reduction catalyst 10 can be greatly reduced as compared with the prior art.

また、バタフライ弁１１の閉時に確保される最小開度の隙間１３の直後にインジェクタ１４の添加口１５を配置したことによって、添加燃料から成るＨＣミストの軽量小粒化を促進し、該ＨＣミストがＮＯx吸蔵還元触媒１０で直ぐにガス化して酸化反応を起こし易くなるようにすることができるので、添加燃料のＮＯx吸蔵還元触媒１０上での反応性を更に向上することができて、より一層効率の良いＮＯx吸蔵還元触媒１０の再生を実現することができる。   Further, by arranging the addition port 15 of the injector 14 immediately after the minimum opening gap 13 secured when the butterfly valve 11 is closed, the HC mist composed of the added fuel is promoted to be lighter and smaller in size. Since the NOx occlusion reduction catalyst 10 can be immediately gasified to easily cause an oxidation reaction, the reactivity of the added fuel on the NOx occlusion reduction catalyst 10 can be further improved and the efficiency can be further improved. A good regeneration of the NOx occlusion reduction catalyst 10 can be realized.

更に、本形態例では排気ブレーキ１２を要する車両を想定し、既存の排気ブレーキ１２を有効に活用して排気絞り手段として流用した例となっているので、新たな排気絞り手段を別途設ける必要がなく、以上に述べた如き車両の減速時に排気流量を絞り込んでＮＯx吸蔵還元触媒１０への燃料添加を行う排気浄化装置の実施コストを著しく削減することができる。   Furthermore, in this embodiment, a vehicle that requires the exhaust brake 12 is assumed, and the existing exhaust brake 12 is effectively utilized as an exhaust throttle means. Therefore, it is necessary to separately provide a new exhaust throttle means. In addition, it is possible to remarkably reduce the implementation cost of the exhaust gas purification apparatus for reducing the exhaust flow rate and adding fuel to the NOx storage reduction catalyst 10 when the vehicle is decelerated as described above.

図３は本発明の別の形態例を示すもので、ディーゼルエンジン１におけるインタークーラ６の出側の吸気管５に配置されているインテークシャッタ２０を、車両の減速時に排気ブレーキ１２のバタフライ弁１１と一緒に絞り込む吸気絞り手段として活用し、制御装置１６により開度信号２０ａを介して制御するようにしてある。   FIG. 3 shows another embodiment of the present invention. An intake shutter 20 disposed in the intake pipe 5 on the outlet side of the intercooler 6 in the diesel engine 1 is replaced with a butterfly valve 11 of the exhaust brake 12 when the vehicle is decelerated. It is used as an intake throttle means for narrowing together with the control signal, and is controlled by the control device 16 via the opening signal 20a.

即ち、インテークシャッタ２０の本来の機能は、ディーゼルエンジン１を停止させる目的で使用されるものであるが、ここでは車両の減速時に排気ブレーキ１２のバタフライ弁１１と一緒に絞り込むようにしている。   That is, the original function of the intake shutter 20 is used for the purpose of stopping the diesel engine 1, but here, it is narrowed together with the butterfly valve 11 of the exhaust brake 12 when the vehicle is decelerated.

而して、このようにすれば、減速時にインテークシャッタ２０により吸気流量が同時に絞り込まれるので、排気ブレーキ１２のバタフライ弁１１で排気の流れが堰き止められることによる排気抵抗の増加作用（排気ブレーキの作用）が得られなくなり、ディーゼルエンジン１側でのポンピングロスが喪失して単なるフリクションのみの惰性運転となる結果、車両の減速時に運転者が意図しない制動力がかかることがなくなる。   Thus, since the intake flow rate is simultaneously reduced by the intake shutter 20 during deceleration, the exhaust resistance is increased by blocking the exhaust flow by the butterfly valve 11 of the exhaust brake 12 (exhaust brake function). (Action) cannot be obtained, and the pumping loss on the diesel engine 1 side is lost, resulting in a coasting operation only with friction, so that a braking force not intended by the driver is not applied when the vehicle is decelerated.

要するに、先に図１及び図２で説明した形態例においては、減速の度に排気ブレーキ１２のバタフライ弁１１のみが閉じていたので、排気の流れが堰き止められることによる排気抵抗の増加作用により制動力がかかってしまうが、これは運転者の意図しないものであるので、アクセルオフ時に単なるフリクションのみの惰性運転となると予想している運転者にとっては、ドラバビリティーに違和感を生じることも考えられる。   In short, in the embodiment described above with reference to FIGS. 1 and 2, since only the butterfly valve 11 of the exhaust brake 12 is closed each time the vehicle is decelerated, the exhaust resistance increases due to the exhaust flow being blocked. Although braking force is applied, this is not intended by the driver, so it may be thought that the driver may feel uncomfortable for the driver who anticipates that it will be inertial driving with only friction when the accelerator is off. It is done.

そこで、減速時に排気ブレーキ１２のバタフライ弁１１と共にインテークシャッタ２０を閉じるようにすれば、排気ブレーキ１２が効かなくなって、車両の減速時に運転者の意図しない制動力がかかることを回避することができ、ドライバビリティを良好に維持することができる。   Therefore, if the intake shutter 20 is closed together with the butterfly valve 11 of the exhaust brake 12 at the time of deceleration, it is possible to prevent the exhaust brake 12 from being effective and applying a braking force not intended by the driver when the vehicle is decelerated. , Drivability can be maintained well.

ただし、運転者が意図的に排気ブレーキ１２を効かせたい場合には、図示しない運転席にある排気ブレーキスイッチのオン信号等を受けた制御装置１６によって、減速時に排気ブレーキ１２のバタフライ弁１１だけを閉じ且つインテークシャッタ２０を開状態に維持するような制御モードに切り替えるようにすれば良い。   However, when the driver wants to apply the exhaust brake 12 intentionally, only the butterfly valve 11 of the exhaust brake 12 at the time of deceleration is controlled by the control device 16 that receives an ON signal of an exhaust brake switch in a driver's seat (not shown). Is switched to a control mode that closes the intake shutter 20 and maintains the intake shutter 20 in the open state.

尚、本発明の排気浄化装置は、上述の形態例にのみ限定されるものではなく、車両の減速に関する判定には先の形態例で説明した手法以外にも各種の手法を用い得ること、また、排気絞り手段には必ずしも排気ブレーキを用いなくても良く、吸気絞り手段にもインテークシャッタ以外の手段を採用し得ること、その他、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。   The exhaust emission control device according to the present invention is not limited to the above-described embodiment. Various determinations other than the method described in the previous embodiment can be used for the determination related to vehicle deceleration. The exhaust throttle means does not necessarily need to use an exhaust brake, and means other than the intake shutter can be adopted as the intake throttle means, and other various modifications can be made without departing from the scope of the present invention. Of course.

本発明を実施する形態の一例を示す概略図である。It is the schematic which shows an example of the form which implements this invention. 図１の排気ブレーキの詳細を示す拡大図である。It is an enlarged view which shows the detail of the exhaust brake of FIG. 本発明の別の形態例を示す概略図である。It is the schematic which shows another form example of this invention.

符号の説明Explanation of symbols

１ ディーゼルエンジン
４ 吸気
５ 吸気管（吸気流路）
８ 排気ガス
９ 排気管（排気流路）
１０ ＮＯx吸蔵還元触媒
１１ バタフライ弁（排気絞り手段）
１２ 排気ブレーキ
１３ 隙間
１４ インジェクタ（燃料添加手段）
１５ 添加口
１６ 制御装置
２０ インテークシャッタ（吸気絞り手段） 1 Diesel engine 4 Intake 5 Intake pipe (intake flow path)
8 Exhaust gas 9 Exhaust pipe (exhaust flow path)
10 NOx storage reduction catalyst 11 Butterfly valve (exhaust throttle means)
12 Exhaust brake 13 Clearance 14 Injector (fuel addition means)
15 Addition port 16 Control device 20 Intake shutter (intake throttle means)

Claims (4)

排気流路の途中にＮＯx吸蔵還元触媒を装備し且つ該ＮＯx吸蔵還元触媒の上流側に還元剤として燃料を添加してＮＯxを還元浄化するように構成した排気浄化装置であって、前記排気流路におけるＮＯx吸蔵還元触媒より上流側に排気流量を適宜に絞り込む排気絞り手段を備えると共に、該排気絞り手段の直後に排気流路内に燃料を添加する燃料添加手段を設け、前記排気絞り手段を車両の減速時に絞り込んで前記燃料添加手段に燃料添加を実行せしめる制御装置を備えたことを特徴とする排気浄化装置。   An exhaust gas purification apparatus equipped with a NOx storage reduction catalyst in the middle of an exhaust flow path and configured to reduce and purify NOx by adding fuel as a reducing agent upstream of the NOx storage reduction catalyst, wherein the exhaust flow An exhaust throttle means for appropriately reducing the exhaust flow rate upstream of the NOx storage reduction catalyst in the passage, and a fuel addition means for adding fuel into the exhaust flow path immediately after the exhaust throttle means, the exhaust throttle means being An exhaust emission control device comprising: a control device that narrows down the vehicle when decelerating and causes the fuel addition means to perform fuel addition. 排気絞り手段をバタフライ弁により構成し、該バタフライ弁の閉時に確保される最小開度の隙間の直後に燃料添加手段の添加口を配置したことを特徴とする請求項１に記載の排気浄化装置。   2. The exhaust emission control device according to claim 1, wherein the exhaust throttle means is constituted by a butterfly valve, and the addition port of the fuel addition means is arranged immediately after the gap of the minimum opening secured when the butterfly valve is closed. . 排気絞り手段を排気ブレーキに兼用させたことを特徴とする請求項１又は２に記載の排気浄化装置。   The exhaust emission control device according to claim 1 or 2, wherein the exhaust throttle means is also used as an exhaust brake. 吸気流路に吸気流量を適宜に絞り込む吸気絞り手段を備え、該吸気絞り手段を車両の減速時に排気絞り手段と一緒に絞り込むように構成したことを特徴とする請求項１、２又は３に記載の排気浄化装置。   4. The intake throttle device according to claim 1, further comprising: an intake throttle means for appropriately reducing an intake flow rate in the intake flow path, wherein the intake throttle means is configured to be reduced together with the exhaust throttle means when the vehicle is decelerated. Exhaust purification equipment.
JP2005028660A 2005-02-04 2005-02-04 Exhaust emission control device Pending JP2006214370A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006233906A (en) * 2005-02-25 2006-09-07 Toyota Motor Corp Exhaust emission control device for internal combustion engine
JP2009156065A (en) * 2007-12-25 2009-07-16 Mitsubishi Motors Corp Exhaust emission control device for internal combustion engine
JP2009203961A (en) * 2008-02-29 2009-09-10 Hino Motors Ltd Exhaust emission control device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006233906A (en) * 2005-02-25 2006-09-07 Toyota Motor Corp Exhaust emission control device for internal combustion engine
JP2009156065A (en) * 2007-12-25 2009-07-16 Mitsubishi Motors Corp Exhaust emission control device for internal combustion engine
JP2009203961A (en) * 2008-02-29 2009-09-10 Hino Motors Ltd Exhaust emission control device

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